Add withPosition() factory method to FileSource

- Refactor creation to avoid redundant canonicalization calls
- Introduced internal factory methods for clearer construction paths

Author: lslonina

junit-platform-engine/src/main/java/org/junit/platform/engine/support/descriptor/FileSource.java

@@ -44,7 +44,7 @@ public class FileSource implements FileSystemSource {
 	 * @param file the source file; must not be {@code null}
 	 */
 	public static FileSource from(File file) {
-		return new FileSource(file);
+		return canonicalized(file, null);
 	}
 
 	/**
@@ -55,27 +55,45 @@ public static FileSource from(File file) {
 	 * @param filePosition the position in the source file; may be {@code null}
 	 */
 	public static FileSource from(File file, @Nullable FilePosition filePosition) {
-		return new FileSource(file, filePosition);
+		return canonicalized(file, filePosition);
+	}
+
+	/**
+	 * Create a new {@code FileSource} from an existing instance but with a different
+	 * {@link FilePosition}. This avoids redundant canonical path resolution.
+	 *
+	 * @param source the existing {@code FileSource}; must not be {@code null}
+	 * @param filePosition the new {@code FilePosition}; may be {@code null}
+	 * @return a new {@code FileSource} with same file and updated position
+	 */
+	public static FileSource withPosition(FileSource source, @Nullable FilePosition filePosition) {
+		Preconditions.notNull(source, "source must not be null");
+		return direct(source.file, filePosition);
 	}
 
 	private final File file;
 
 	@Nullable
 	private final FilePosition filePosition;
 
-	private FileSource(File file) {
-		this(file, null);
-	}
-
 	private FileSource(File file, @Nullable FilePosition filePosition) {
+		this.file = file;
+		this.filePosition = filePosition;
+	}
+	
+	private static FileSource canonicalized(File file, @Nullable FilePosition filePosition) {
 		Preconditions.notNull(file, "file must not be null");
 		try {
-			this.file = file.getCanonicalFile();
+			return new FileSource(file.getCanonicalFile(), filePosition);
 		}
 		catch (IOException ex) {
 			throw new JUnitException("Failed to retrieve canonical path for file: " + file, ex);
 		}
-		this.filePosition = filePosition;
+	}
+
+	private static FileSource direct(File file, @Nullable FilePosition filePosition) {
+		Preconditions.notNull(file, "file must not be null");
+		return new FileSource(file, filePosition);
 	}
 
 	/**